index.js

const visit = require("unist-util-visit");
const toString = require("mdast-util-to-string")

module.exports = ({ markdownAST }, pluginOptions) => {
  const trie = getTrie(pluginOptions.dictionary);
  visit(markdownAST, "paragraph", (node) => {
    addDictionaryDefinitions(node, trie);
  });

  return markdownAST
}

const getTrie = (dictionary) => {
  const trie = {};

  dictionary.forEach(definition => {
      definition.matchers.forEach(matcher => {
          let trieMatcherNode = trie;
          const matcherWords = matcher.toLowerCase().split(' ');
          matcherWords.forEach(word => {
              trieMatcherNode[word] = trieMatcherNode[word] || {};
              trieMatcherNode = trieMatcherNode[word];
          });

          trieMatcherNode.definition = definition;
      });
  });

  return trie;
}

const addDictionaryDefinitions = (node, trie) => {
  // Grab the innerText of the paragraph node
  let originalText = text = toString(node);
  const textSplittedToWords = text.toLowerCase().split(' ');

  let currPlaceInTrie = trie, streakTextIndex = null, currTextIndex = 0;
  for (let i = 0; i < textSplittedToWords.length; i++) {
      const currWord = textSplittedToWords[i];

      const nextPlaceInTrie = currPlaceInTrie[currWord];
      if (!nextPlaceInTrie) {
          streakTextIndex = null;
          currPlaceInTrie = trie;
      } else if (!nextPlaceInTrie.definition) {
          streakTextIndex = streakTextIndex || currTextIndex;
          currPlaceInTrie = nextPlaceInTrie;
      } else {
          streakTextIndex = streakTextIndex || currTextIndex;
          const end = currTextIndex + currWord.length;
          const oldPart = text.substring(streakTextIndex, end);
          const linkVal = nextPlaceInTrie.definition.title ? `<abbr title="${nextPlaceInTrie.definition.title}">${oldPart}</abbr>`: oldPart;
          const linkText = nextPlaceInTrie.definition.link ? `<a class="dict-link" href="${nextPlaceInTrie.definition.link}">${linkVal}</a>` : linkVal;
          text = text.substring(0, streakTextIndex) + linkText + text.substring(end);
          currTextIndex += linkText.length - oldPart.length + 1;
          continue;
      }

      currTextIndex += currWord.length + 1;
  }

  if (originalText !== text) {
      const parentChildrenArray = node.children;
      const indexOfTextNodeInParent = parentChildrenArray.findIndex((n) => n.value === originalText);
      parentChildrenArray.splice(indexOfTextNodeInParent, 1, {
          type: 'html',
          value: text
      });
  }
}